Methacrylate Silatrane: New Building Block for Development of Functional Polymeric Coatings through Controlled Silanization.

Abstract

Organosilicons are prevalent for the development of nanostructures, adhesives, fillers, and surface functionalization due to their ease of operation, availability, and effective modification on various surfaces. 3-(Trimethoxysilyl) propyl methacrylate (TMSPMA) is a widely used commercial silane for designing hybrid polymers via radical polymerization for a wide spectrum of applications. However, the chemical stability and processibility of TMSPMA encounter burdens due to its susceptibility to hydrolysis and aggregation, resulting in limiting its functionality and implementations. In this work, methylacrylate silatrane (MAST) was newly developed to bear a chemically stable tricyclic caged silatranyl ring and a transannular N → Si dative bond for excellent stability, processability, and progressive deposition. A complete, uniform, and thin assembled adlayer of MAST on a silicon wafer was verified by a contact angle goniometer, ellipsometry, atomic force microscopy, X-ray photoelectron microscopy, and Fourier transform infrared spectroscopy. The good homogeneity and molecular orientation of the MAST coatings are attributed to controlled silanization on oxide surfaces and strong intermolecular hydrogen bonds between internal urea groups. Moreover, the zwitterionic monomer of 2-methacryloyloxyethyl phosphorylcholine (MPC) was employed to copolymerize with MAST or TMSPMA to afford macromolecular modifiers of p(MPC9-co-MAST1) and p(MPC9-co-TMSPMA1), respectively, for surface modification and antifouling properties on silicon substrates. p(MPC9-co-MAST1) well preserved the reactivity of the silatrane groups after the polymerization process, whereas the hydrolysis of silane groups of p(MPC9-co-TMSPMA1) obviously occurred, giving rise to aggregation of polymer chains. Therefore, the p(MPC9-co-MAST1) film on surfaces exhibited superior wettability, grafting density, and antifouling properties compared to p(MPC9-co-TMSPMA1). Accordingly, we envision the great potential of the MAST building block for the development of functional hybrid polymers, well-defined polymeric thin films, and nanomaterials.